161868881 has 2 divisors, whose sum is σ = 161868882. Its totient is φ = 161868880.

The previous prime is 161868877. The next prime is 161868901. The reversal of 161868881 is 188868161.

It is a happy number.

161868881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 161696656 + 172225 = 12716^2 + 415^2 .

It is a cyclic number.

It is not a de Polignac number, because 161868881 - 2² = 161868877 is a prime.

It is a super-2 number, since 2×161868881² = 52403069272384322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161868281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80934440 + 80934441.

It is an arithmetic number, because the mean of its divisors is an integer number (80934441).

Almost surely, 2^161868881 is an apocalyptic number.

It is an amenable number.

161868881 is a deficient number, since it is larger than the sum of its proper divisors (1).

161868881 is an equidigital number, since it uses as much as digits as its factorization.

161868881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 147456, while the sum is 47.

The square root of 161868881 is about 12722.7701779133. The cubic root of 161868881 is about 544.9890646741.

The spelling of 161868881 in words is "one hundred sixty-one million, eight hundred sixty-eight thousand, eight hundred eighty-one".